1. Field of the Invention
The invention relates to a dual fuel tank system having a single fuel filler inlet for a vehicle.
2. Background
Multiple fuel tank systems for automotive vehicles are well known, for increasing fuel capacity in an automotive vehicle to increase its driving range. Numerous methods have been employed to provide a filling capability for the multiple fuel tanks as well as the capability for drawing fuel from those tanks to feed the internal combustion engine of the vehicle. Structures for filling the fuel tanks have ranged from having individual fuel inlet ports, for instance on each side of the vehicle, to a single fuel inlet port with a Y-type connector to split the fuel flow. Another system, disclosed in U.S. Pat. No. 5,983,932 and commonly owned, comprises a cross-flow pipe between the multiple fuel tanks to allow simultaneous filling of the fuel tanks from a single inlet port. As the fuel level in a first fuel tank rises, the fuel will naturally flow to the second fuel tank, the fuel seeking its own level between the connected tanks.
An alternative method of filling multiple fuel tanks is disclosed in U.S. Pat. No. 4,765,359, which discloses multiple fuel inlet ports, preferably located on opposite sides of an automotive vehicle, connected to a common fuel tank filling manifold, whereby pumping fuel into either of the inlet ports directs fuel into the manifold, thereby filling the fuel tanks.
A common limitation of the prior art fuel tank systems is that effective filling of the multiple fuel tanks is largely dependent upon relative fill levels between tanks, fuel and ambient temperature, fuel reid vapor pressure, and vehicle attitude. For instance, when vehicle packaging forces the tanks to be positioned at different elevations, the fuel tank with the smaller pressure drop between the filler neck and the tank will be filled sooner than the tank with the higher pressure drop, thus potentially shutting off the fuel flow prior to complete filling of the tanks. Premature nozzle shut-off and fuel spit-back through the fuel inlet port are undesirable to a customer.
A further consideration is that fuel systems today must meet certain government mandated onboard refueling vapor recovery standards. This means that the system shall capture a minimum of 95% of the fuel vapors during a specific fill test. Thus, the vapors escaping from the filler neck must be less than or equal to 5% of the fuel vapors generated during a refill event.
It would be advantageous to provide a dual tank simultaneous fill system that is adaptable to filling both tanks to capacity under all operating conditions and fuel characteristics.
The invention relates to a fuel supply system for an automotive vehicle of the type having an internal combustion engine, the fuel supply system including two fuel storage tanks, a fuel pumping mechanism for transporting fuel from at least one of the storage tanks to the engine, a fuel transfer system for conveying fuel from one of the storage tanks to another of the storage tanks, and a fuel filling system for adding fuel to the system from a gas station, the fuel filling system comprising a single fuel inlet line. The fuel supply system further includes a manifolded Y-connector fluidly connecting the fuel inlet port with the two fuel storage tanks. The manifolded Y-connector is comprised of a manifolded section, an inlet port depending from an upper end of the manifolded section and in fluid communication with the fluid inlet line, and two outlet ports depending from a lower wall of the manifolded section. Each of the two outlet ports are fluidly connected to one of the first and second tanks. Where upon filling the fuel supply system, the manifolded Y-connector operates to first deliver fuel to the first tank and then to fill the second tank, while accommodating filling turbulence.
Other features of the invention will be apparent from the ensuing description in conjunction with the accompanying drawings.